The spokesman added that the guidance, from the umbrella body, Universities UK (UUK), should be urgently reviewed.

"There is an important issue of principle here around segregation.

"There is a very important tradition of free speech in our educational institutions," he said.

Court 'clarification'

"It is important to be vigilant regarding free speech," the spokesman said. But he added: "This is about universities, places of worship are a very different issue."

Yesterday, Universities UK said that its guidance may need to be tested in court.

The body wrote to the Equality and Human Rights Commission (EHRC) asking it to consider having the issue clarified by the High Court, "or provide a clear and public statement about the law and the relevant policy considerations".

UUK also published legal advice on its guidance from Fenella Morris QC which concludes that it "is lawful and provides an appropriate foundation for lawful decision-making by universities".

The row hinges on a hypothetical case study included in the guidance which was published last month.

The case study, now withdrawn pending the EHRC review, involved an external speaker invited to talk about his orthodox religious faith who subsequently requested segregated seating areas for men and women.

The UUK guidance stated that university officials should consider both freedom of speech obligations, as well as discrimination and equality laws when considering the request.

Universities UK concluded: "If neither women nor men were disadvantaged and a non-segregated seating area were also provided, it might in the specific circumstances of the case be appropriate for the university to agree to the request."

It added that the guidance was not prescriptive but was intended to provide "practical assistance to universities in making decisions about who they choose to invite to speak on campus, steering them through all the different considerations, legal and otherwise, that apply."

The row has sparked protests from students and some MPs.

We are working with our lawyers and the EHRC to clarify the position. Meanwhile, the case study which triggered this debate has been withdrawn pending this reviewNicola Dandridge, Universities UK chief executive

While former home secretary Jack Straw said it was "wrong" for universities "to indulge in such extraordinary behaviour".

Equality law

Nicola Dandridge, chief executive of Universities UK, said her organisation agreed entirely with the prime minister that universities should not enforce gender segregation on audiences at the request of guest speakers.

But she added that "where the gender segregation is voluntary, the law is unclear.

"We are working with our lawyers and the EHRC to clarify the position. Meanwhile, the case study which triggered this debate has been withdrawn pending this review."

EHRC chief executive Mark Hammond said it is not "permissible" under the law for universities to segregate by gender in academic meetings.

"Clearly, a university like any other institution is entitled to provide services and facilities separately by gender where appropriate and lawful - for example, accommodation, sports and targeted welfare provision," said Mr Hammond.

"It is also entirely permissible for a university or other organisation to have private members' clubs for a single sex.

"Universities can also provide facilities for religious meetings and associations based on faith, as in the rest of society. Equality law permits gender segregation in premises that are permanently or temporarily being used for the purposes of an organised religion where its doctrines require it."

A statement from the Department for Business, Innovation and Skills said gender segregation is never acceptable on campuses.

"But the application of the law where the segregation is voluntary is unclear which is why Universities UK are working with their lawyers and the EHRC to clarify the position."

The statement added that many universities had very strong equalities policies which ban segregated events on campuses, with some events cancelled recently because the organisers were insisting on segregation.

Ms Dandridge also said it was possible for women to choose to be educated in an all-women environment.

She said it was was not something so alien to our culture "that it has to be regarded like race segregation."